The conspirators were earlier designated positions in secret to form a government that would take office after the assassination of Hitler were it to prove successful. Because of the plot's utter failure, such a government would never rise to power and most of its members were executed. The following were appointed these roles as of July 1944:
http://en.wikipedia.org/wiki/July_20_Plot
Generaloberst Ludwig Beck (Army) - President
Carl Goerdeler (DNVP) - Chancellor
Wilhelm Leuschner (SPD) - Vice-Chancellor
Paul Löbe (SPD) - President of the Reichstag
Julius Leber (SPD) or Eugen Bolz (Centre Party) - Minister of the Interior
Friedrich Werner von der Schulenburg or Ulrich von Hassell - Foreign Minister
Ewald Loeser - Minister of Finance
Friedrich Olbricht (Army) - Minister of War
Hans Oster (Army) - President of the Reichskriegsgericht (military supreme court)
Hans Koch (Confessing Church) - President of the Reichsgericht (supreme court)
Bernhard Letterhaus (catholic trade unionist) - Reconstruction Minister (Minister without portfolio if not appointed)
Karl Blessing - Minister of Economics or President of the Reichsbank
Paul Lejeune-Jung (DNVP) - Minister of Economics
Andreas Hermes (Centre Party) - Minister of Agriculture
Josef Wirmer (Centre Party) - Minister of Justice
The only German political force which was not involved was the Communist Party (KPD).
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The Allied would not allow a conditional surrender. Stauffenberg´s government could not take control and there would be civil war.In the end the only good thing would shorter war, probably. Unless Himmler or Göring perhaps could take control from Stauffenberg et co.